Systems and methods for treating a metal substrate

ABSTRACT

Disclosed is a system for treating a metal substrate comprising a conversion composition comprising trivalent chromium in an amount of 0.001 g/L to 20 g/L and a sealing composition comprising an ammonium-containing compound. Also disclosed is a method for treating a metal substrate that includes contacting at least a portion of a surface of the substrate with the conversion composition and then contacting at least a portion of the surface of the substrate with the sealing composition. Also disclosed is a substrate obtainable by treatment with the system and/or obtainable by the method of treatment.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent Application No. 62/953,762, filed on Dec. 26, 2019, and entitled “Systems and Methods for Treating a Metal Substrate.”

FIELD OF THE INVENTION

The present invention relates to compositions, systems and methods for treating a substrate. The present invention also relates to a substrate obtainable by treatment with the systems and methods.

BACKGROUND OF THE INVENTION

To prevent the oxidation and degradation of metals used in aerospace, automotive, and commercial industries, an inorganic protective coating can be applied to the metal surface. This inorganic protective coating, also referred to as a conversion coating, may be the only coating applied to the metal substrate or the coating may be an intermediate coating to which subsequent coatings are applied.

SUMMARY OF THE INVENTION

Disclosed herein is a system for treating a substrate comprising: a conversion composition comprising trivalent chromium in an amount of 0.001 g/L to 20 g/L based on total weight of the conversion composition; and a sealing composition comprising an ammonium-containing compound.

Also disclosed herein is a method of treating a metal substrate comprising: contacting at least a portion of the surface of the substrate with a conversion composition comprising a trivalent chromium in an amount of 0.001 g/L to 20 g/L based on total weight of the conversion composition; and contacting the portion of the substrate surface that has been treated with the conversion composition with a sealing composition comprising an ammonium-containing compound.

Also disclosed is a substrate obtainable by treatment with a system of the present invention and/or obtainable by the method of treating of the present invention.

Also disclosed is a substrate comprising a surface having a fluoride content of less than 7 atomic percent at the air-surface interface as measured by XPS depth profiling (using a Physical Electronics VersaProbe II instrument equipped with a monochromatic Al kα x-ray source (hv=1,486.7 eV) and a concentric hemispherical analyzer) and/or a fluoride content of less than 4.5 atomic percent 50 nm to 100 nm below the air-surface interface as measured by XPS depth profiling (using a Physical Electronics VersaProbe II instrument equipped with a monochromatic Al kα x-ray source (hv=1,486.7 eV) and a concentric hemispherical analyzer).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an XPS depth profile of (A) substrate treated according to Example 1, (B) substrate treated according to Example 4, and (C) fluoride levels at and below the air-substrate interface in the substrate of Examples 1 and 4.

DETAILED DESCRIPTION OF THE INVENTION

For purposes of the following detailed description, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in any operating examples, or where otherwise indicated, all numbers such as those expressing values, amounts, percentages, ranges, subranges and fractions may be read as if prefaced by the word “about,” even if the term does not expressly appear. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Where a closed or open-ended numerical range is described herein, all numbers, values, amounts, percentages, subranges and fractions within or encompassed by the numerical range are to be considered as being specifically included in and belonging to the original disclosure of this application as if these numbers, values, amounts, percentages, subranges and fractions had been explicitly written out in their entirety.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard variation found in their respective testing measurements.

As used herein, unless indicated otherwise, a plural term can encompass its singular counterpart and vice versa, unless indicated otherwise. For example, although reference is made herein to “a” cleaner composition, “a” conversion composition, and “a” sealing composition, a combination (i.e., a plurality) of these components can be used. In addition, in this application, the use of “or” means “and/or” unless specifically stated otherwise, even though “and/or” may be explicitly used in certain instances.

As used herein, “including,” “containing” and like terms are understood in the context of this application to be synonymous with “comprising” and are therefore open-ended and do not exclude the presence of additional undescribed and/or unrecited elements, materials, ingredients and/or method steps. As used herein, “consisting of” is understood in the context of this application to exclude the presence of any unspecified element, ingredient and/or method step. As used herein, “consisting essentially of” is understood in the context of this application to include the specified elements, materials, ingredients and/or method steps “and those that do not materially affect the basic and novel characteristic(s)” of what is being described. As used herein, open-ended terms are intended to cover “consisting essentially of” and “consisting of.”

As used herein, the terms “on,” “onto,” “applied on,” “applied onto,” “formed on,” “deposited on,” “deposited onto,” mean formed, overlaid, deposited, and/or provided on but not necessarily in contact with the surface. For example, a coating layer “formed over” a substrate does not preclude the presence of one or more other intervening coating layers of the same or different composition located between the formed coating layer and the substrate.

Unless otherwise disclosed herein, the term “substantially free,” when used with respect to the absence of a particular material, means that such material, if present at all in a composition, a bath containing the composition, and/or layers formed from and comprising the composition, only is present in a trace amount of 5 ppm or less based on a total weight of the composition or layer(s), as the case may be, excluding any amount of such material that may be present or derived as a result of drag-in, substrate(s), and/or dissolution of equipment. Unless otherwise disclosed herein, the term “essentially free,” when used with respect to the absence of a particular material, means that such material, if present at all in a composition, a bath containing the composition, and/or layers formed from and comprising the composition, only is present in a trace amount of 1 ppm or less based on a total weight of the composition or layer(s), as the case may be. Unless otherwise disclosed herein, the term “completely free,” when used with respect to the absence of a particular material, means that such material, if present at all in a composition, a bath containing the composition, and/or layers formed from and comprising the composition, is absent from the composition, the bath containing the composition, and/or layers formed from and comprising same (i.e., the composition, bath containing the composition, and/or layers formed from and comprising the composition contain 0 ppm of such material).

As used herein, a “salt” refers to an ionic compound made up of cations and anions and having an overall electrical charge of zero. Salts may be hydrated or anhydrous.

As used herein, “aqueous composition” refers to solution or dispersion in a medium that comprises predominantly water. For example, the aqueous composition may comprise water in an amount of more than 50 wt. %, or more than 70 wt. % or more than 80 wt. % or more than 90 wt. % or more than 95 wt. %, based on the total weight of the composition. The aqueous medium may for example consist substantially of water. For example, the aqueous composition may comprise solutes or dispersants in an amount of at least 5 wt. %, such as at least 10 wt. %, such as at least 20 wt. %, such as at least 30 wt. %, such as at least 40 wt. %, such as at least 50 wt. % based on total weight of the aqueous composition.

As used herein, “conversion composition” refers to a composition that is capable of reacting with and chemically altering the substrate surface and binding to it to form a film that affords corrosion protection.

As used herein, a “sealing composition” refers to a composition, e.g. a solution or dispersion, that affects a substrate surface or a material deposited onto a substrate surface in such a way as to alter the physical and/or chemical properties of the substrate surface (i.e., the composition affords corrosion protection) and that is applied to at least a portion of the substrate surface following treatment of the surface with a conversion composition.

As used herein, a “system” refers to a plurality of treatment compositions (including cleaners and rinses) used to treat a substrate and to produce a treated substrate. The system may be part of a production line (such as a factory production line) that produces a finished substrate or a treated substrate that is suitable for use in other production lines.

As used herein, the term “ammonium-containing compound” refers to a compound that contains the NH₄ ⁺ cation.

As used herein, the term “transition metal” refers to an element that is in any of Groups IIIB to XIIB of the CAS version of the Periodic Table of Elements as is shown, excluding the lanthanide series elements and elements 89-103, for example, in the Handbook of Chemistry and Physics, 63^(rd) edition (1983), corresponding to Groups 3 to 12 in the actual IUPAC numbering.

As used herein, the term “transition metal compound” refers to compounds that include at least one element that is a transition metal of the CAS version of the Periodic Table of the Elements.

As used herein, the term “Group IA metal” refers to an element that is in Group IA of the CAS version of the Periodic Table of the Elements as is shown, for example, in the Handbook of Chemistry and Physics, 63^(rd) edition (1983), corresponding to Group 1 in the actual IUPAC numbering.

As used herein, the term “Group IA metal compound” refers to compounds that include at least one element that is in Group IA of the CAS version of the Periodic Table of the Elements.

As used herein, the term “Group IIA metal” refers to an element that is in Group IIA of the CAS version of the Periodic Table of the Elements as is shown, for example, in the Handbook of Chemistry and Physics, 63^(rd) edition (1983), corresponding to Group 2 in the actual IUPAC numbering.

As used herein, the term “Group IIA metal compound” refers to compounds that include at least one element that is in Group IIA of the CAS version of the Periodic Table of the Elements.

As used herein, the term “Group IIIB metal” refers to yttrium and scandium of the CAS version of the Periodic Table of the Elements as is shown, for example, in the Handbook of Chemistry and Physics, 63^(rd) edition (1983), corresponding to Group 3 in the actual IUPAC numbering. For clarity, “Group IIIB metal” expressly excludes lanthanide series elements.

As used herein, the term “Group IIIB metal compound” refers to compounds that include at least one element that is in group IIIB of the CAS version of the Periodic Table of the Elements as defined above.

As used herein, the term “Group IVB metal” refers to an element that is in group IVB of the CAS version of the Periodic Table of the Elements as is shown, for example, in the Handbook of Chemistry and Physics, 63^(rd) edition (1983), corresponding to Group 4 in the actual IUPAC numbering.

As used herein, the term “Group IVB metal compound” refers to compounds that include at least one element that is in Group IVB of the CAS version of the Periodic Table of the Elements.

As used herein, the term “Group VB metal” refers to an element that is in group VB of the CAS version of the Periodic Table of the Elements as is shown, for example, in the Handbook of Chemistry and Physics, 63^(rd) edition (1983), corresponding to Group 5 in the actual IUPAC numbering.

As used herein, the term “Group VB metal compound” refers to compounds that include at least one element that is in Group VB of the CAS version of the Periodic Table of the Elements.

As used herein, the term “Group VIB metal” refers to an element that is in group VIB of the CAS version of the Periodic Table of the Elements as is shown, for example, in the Handbook of Chemistry and Physics, 63^(rd) edition (1983), corresponding to Group 6 in the actual IUPAC numbering.

As used herein, the term “Group VIB metal compound” refers to compounds that include at least one element that is in Group VIB of the CAS version of the Periodic Table of the Elements.

As used herein, the term “Group VIIB metal” refers to an element that is in group VIIB of the CAS version of the Periodic Table of the Elements as is shown, for example, in the Handbook of Chemistry and Physics, 63^(rd) edition (1983), corresponding to Group 7 in the actual IUPAC numbering.

As used herein, the term “Group VIIB metal compound” refers to compounds that include at least one element that is in Group VIIB of the CAS version of the Periodic Table of the Elements.

As used herein, the term “Group IIB metal” refers to an element that is in group IIB of the CAS version of the Periodic Table of the Elements as is shown, for example, in the Handbook of Chemistry and Physics, 63^(rd) edition (1983), corresponding to Group 12 in the actual IUPAC numbering.

As used herein, the term “Group IIB metal compound” refers to compounds that include at least one element that is in Group IIB of the CAS version of the Periodic Table of the Elements.

As used herein, the term “lanthanide series elements” refers to elements 57-71 of the CAS version of the Periodic Table of the Elements and includes elemental versions of the lanthanide series elements. According to the invention, the lanthanide series elements may be those which have both common oxidation states of +3 and +4, referred to hereinafter as +3/+4 oxidation states.

As used herein, the term “lanthanide compound” refers to compounds that include at least one of elements 57-71 of the CAS version of the Periodic Table of the Elements.

As used herein, the term “halogen” refers to any of the elements fluorine, chlorine, bromine, iodine, and astatine of the CAS version of the Periodic Table of the Elements, corresponding to Group VIIA of the periodic table.

As used herein, the term “halide” refers to compounds that include at least one halogen.

As used herein, the term “aluminum,” when used in reference to a substrate, refers to substrates made of or comprising aluminum and/or aluminum alloy, and clad aluminum substrates.

Pitting corrosion is the localized formation of corrosion by which cavities or holes are produced in a substrate. The term “pit,” as used herein, refers to such cavities or holes resulting from pitting corrosion and is characterized by (1) a rounded, elongated or irregular appearance when viewed normal to the test panel surface, (2) a “comet-tail”, a line, or a “halo” (i.e., a surface discoloration) emanating from the pitting cavity, and (3) the presence of corrosion byproduct (e.g., white, grayish or black granular, powdery or amorphous material) inside or immediately around the pit. An observed surface cavity or hole must exhibit at least two of the above characteristics to be considered a corrosion pit. Surface cavities or holes that exhibit only one of these characteristics may require additional analysis before being classified as a corrosion pit.

Unless otherwise disclosed herein, as used herein, the terms “total composition weight”, “total weight of a composition” or similar terms refer to the total weight of all ingredients being present in the respective composition including any carriers and solvents.

The present invention is directed to a system for treating a metal substrate comprising, or in some instances, consisting essentially of, or in some instances, consisting of: a conversion composition comprising trivalent chromium in an amount of 0.001 g/L to 20 g/L based on total weight of the conversion composition; and a sealing composition comprising an ammonium-containing compound. The present invention also is directed to a method of treating a metal substrate comprising, or in some instances, consisting essentially of, or in some instances, consisting of: contacting at least a portion of a surface of the substrate with a conversion composition comprising trivalent chromium in an amount of 0.001 g/L to 20 g/L based on total weight of the conversion composition; and contacting at least a portion of the surface that has been contacted with the conversion composition with a sealing composition comprising ammonium-containing compound.

Suitable substrates that may be used in the present invention include metal substrates, metal alloy substrates, and/or substrates that have been metallized, such as nickel-plated plastic. According to the present invention, the metal or metal alloy can comprise or be steel, aluminum, zinc, nickel, and/or magnesium. For example, the steel substrate could be cold rolled steel, hot rolled steel, electrogalvanized steel, and/or hot dipped galvanized steel. Aluminum alloys of the 1XXX, 2XXX, 3XXX, 4XXX, 5XXX, 6XXX, or 7XXX series as well as clad aluminum alloys also may be used as the substrate. Aluminum alloys may comprise 0.01% by weight copper to 10% by weight copper. Aluminum alloys which are treated may also include castings, such as 1XX.X, 2XX.X, 3XX.X, 4XX.X, 5XX.X, 6XX.X, 7XX.X, 8XX.X, or 9XX.X (e.g., A356.0). Magnesium alloys of the AZ31B, AZ91C, AM60B, or EV31A series also may be used as the substrate. The substrate used in the present invention may also comprise titanium and/or titanium alloys, zinc and/or zinc alloys, and/or nickel and/or nickel alloys. According to the present invention, the substrate may comprise a portion of a vehicle such as a vehicular body (e.g., without limitation, door, body panel, trunk deck lid, roof panel, hood, roof and/or stringers, rivets, landing gear components, and/or skins used on an aircraft) and/or a vehicular frame. As used herein, “vehicle” or variations thereof includes, but is not limited to, civilian, commercial and military aircraft, and/or land vehicles such as cars, motorcycles, and/or trucks.

As mentioned above, the conversion composition of the present invention may comprise a conversion composition comprising trivalent chromium. The conversion composition may further comprise an anion that may be suitable for forming a salt with a trivalent chromium cation, including for example a sulfate, a nitrate, an acetate, a carbonate, a hydroxide, or combinations thereof.

According to the present invention, the trivalent chromium salt may be present in the conversion composition in an amount of at least 0.001 g/L, such as at least 0.1 g/L, such as at least 0.5 g/L, and in some instances, no more than 20 g/L, such as no more than 10 g/L, such as no more than 5 g/L. According to the present invention, the trivalent chromium salt may be present in the conversion composition in an amount of 0.001 g/L to 20 g/L, such as 0.1 g/L to 10 g/L, such as 0.5 g/L to 5 g/L.

Optionally, according to the present invention, the conversion composition also may comprise a metal such as a Group I and/or a Group II metal. For example, the Group I and/or Group II metal may be present as a metal salt. In such instances, the anion forming the salt with a Group I and/or Group II cation may comprise, for example, a halogen, a nitrate, a sulfate, an acetate, a phosphate, a silicate (e.g., orthosilicates and metasilicates), a carbonate, an hydroxide, and the like.

Optionally, according to the present invention, the conversion composition also may comprise at least one coinhibitor. In examples, the coinhibitor may comprise a Group IIA metal, a transition metal, a lanthanide series metal, an azole, or combinations thereof. According to the present invention, the lanthanide series may, for example, comprise cerium, praseodymium, terbium, or combinations thereof; the Group IIA metal may comprise magnesium; the transition metal may comprise a Group IIIB metal such as yttrium, scandium, or combinations thereof, a Group IVB metal such as zirconium, titanium, hafnium, or combinations thereof, a Group VB metal such as vanadium, a Group VIB metal such as molybdenum, a Group VIM metal such as manganese; and/or a Group IIB metal such as zinc. As used herein, “coinhibitor” refers to a metal or other compound present in the conversion composition in addition to the trivalent chromium to reduce pitting on the substrate surface (i.e., an improvement in corrosion performance).

According to the present invention, the conversion composition may further comprise an anion that may be suitable for forming a salt with the conversion composition metal cations of the coinhibitor(s), such as a halogen, a nitrate, a sulfate, a phosphate, a silicate (e.g., orthosilicates and metasilicates), a carbonate, an acetate, a hydroxide, and the like.

According to the present invention, the salt of the coinhibitor of the conversion composition may be present in the conversion composition in an amount of at least 0.001 g/L, such as at least 0.1 g/L, such as at least 0.5 g/L, and in some instances, no more than 20 g/L, such as no more than 10 g/L, such as no more than 5 g/L. According to the present invention, the salt of the coinhibitor of the conversion composition may be present in the conversion composition in an amount of 0.001 g/L to 20 g/L, such as 0.1 g/L to 10 g/L, such as 0.5 g/L to 5 g/L.

According to the present invention, the conversion composition may exclude hexavalent chromium or compounds that include hexavalent chromium. Non-limiting examples of such materials include chromic acid, chromium trioxide, chromic acid anhydride, dichromate salts, such as ammonium dichromate, sodium dichromate, potassium dichromate, and calcium, barium, magnesium, zinc, cadmium, and strontium dichromate. When a conversion composition and/or a coating or a layer, respectively, formed from the same is substantially free, essentially free, or completely free of hexavalent chromium, this includes hexavalent chromium in any form, such as, but not limited to, the hexavalent chromium-containing compounds listed above.

Thus, optionally, according to the present invention, the conversion compositions and/or coatings or layers, respectively, deposited from the same may be substantially free, may be essentially free, and/or may be completely free of one or more of any of the elements or compounds listed in the preceding paragraph. A conversion composition and/or coating or layer, respectively, formed from the same that is substantially free of hexavalent chromium or derivatives thereof means that hexavalent chromium or derivatives thereof are not intentionally added, but may be present in trace amounts, such as because of impurities or unavoidable contamination from the environment. In other words, the amount of material is so small that it does not affect the properties of the conversion composition; in the case of hexavalent chromium, this may further include that the element or compounds thereof are not present in the conversion compositions and/or coatings or layers, respectively, formed from the same in such a level that it causes a burden on the environment. The term “substantially free” means that the conversion compositions and/or coating or layers, respectively, formed from the same contain less than 10 ppm of any or all of the elements or compounds listed in the preceding paragraph, based on total weight of the composition or the layer, respectively, if any at all. The term “essentially free” means that the conversion compositions and/or coatings or layers, respectively, formed from the same contain less than 1 ppm of any or all of the elements or compounds listed in the preceding paragraph, if any at all. The term “completely free” means that the conversion compositions and/or coatings or layers, respectively, formed from the same contain less than 1 ppb of any or all of the elements or compounds listed in the preceding paragraph, if any at all.

According to the present invention, the pH of the conversion composition may, in some instances, be less than 7, such as less than 5, such as 1.5 to 6.9, such as 2.0 to 6.0, such as 2.5 to 4.5. The pH may be adjusted using, for example, any acid and/or base as is necessary. Thus, according to the present invention, the pH of the conversion composition may be maintained through the inclusion of an acidic material, including water soluble and/or water dispersible acids, such as nitric acid, sulfuric acid, and/or phosphoric acid. Additionally, according to the present invention, the pH of the composition may be maintained through the inclusion of a basic material, including water soluble and/or water dispersible bases, such as sodium hydroxide, sodium carbonate, potassium carbonate, potassium hydroxide, ammonium hydroxide, ammonia, and/or amines such as triethylamine, methylethyl amine, or mixtures thereof

The conversion composition may comprise an aqueous medium and may optionally contain other materials such as nonionic surfactants and auxiliaries conventionally used in the art of conversion compositions. In the aqueous medium, water dispersible organic solvents, for example, alcohols with up to about 8 carbon atoms such as methanol, isopropanol, and the like, may be present; or glycol ethers such as the monoalkyl ethers of ethylene glycol, diethylene glycol, or propylene glycol, and the like. When present, water dispersible organic solvents are typically used in amounts up to about ten percent by volume, based on the total volume of aqueous medium. Additionally, in the aqueous medium, thickeners such as cellulosic, silicated, or acrylic thickeners may be present. When present, such thickeners are typically used in amounts of at least 0.00001% by weight, such as at least 0.5% by weight, and in some instances, no more than 5% by weight, such as no more than 1% by weight. When present such thickeners are typically used in amounts of 0.00001% to 5% by weight, such as 0.5% to 1% by weight.

Other optional materials include surfactants that function as defoamers or substrate wetting agents. Anionic, cationic, amphoteric, and/or nonionic surfactants may be used. Defoaming surfactants may optionally be present at levels up to 1 weight percent, such as up to 0.1 percent by weight, and wetting agents are typically present at levels up to 2 percent, such as up to 0.5 percent by weight, based on the total weight of the conversion composition.

As mentioned above, the conversion composition may comprise a carrier, often an aqueous medium, so that the composition is in the form of a solution or dispersion of the trivalent chromium cation and optionally other metal ions and/or coinhibitors in the carrier. According to the present invention, the solution or dispersion may be brought into contact with the substrate by any of a variety of known techniques, such as dipping or immersion, spraying, intermittent spraying, dipping followed by spraying, spraying followed by dipping, brushing, or roll-coating. According to the invention, the solution or dispersion, when applied to the metal substrate, is at a temperature ranging from 40° F. to 160° F., such as 60° F. to 110° F., such as 70° F. to 90° F. For example, the conversion process may be carried out at ambient conditions. The contact time is often from 1 second to 30 minutes, such as 30 seconds to 15 minutes, such as 4 minutes to 10 minutes. As used herein, “ambient conditions” refer to room temperature and humidity conditions or temperature and humidity conditions that are typically found in the area in which the coating composition is being applied to a substrate, e.g., at 10° C. to 40° C. and 5% to 80% relative humidity, while slightly thermal conditions are temperatures that are slightly above ambient temperature (e.g., >40° C. and less than 100° C. at 5% to 80% relative humidity)

According to the present invention, following the contacting with the conversion composition, the substrate optionally may be air dried at room temperature or may be dried with hot air, such as slightly thermal air, for example, by using an air knife, by flashing off the water by brief exposure of the substrate to a high temperature (i.e., a temperature greater than ambient), such as by drying the substrate in an oven at 15° C. to 100° C., such as 20° C. to 90° C., or in a heater assembly using, for example, infrared heat, such as for 10 minutes at 70° C., or by passing the substrate between squeegee rolls. According to the present invention, following the contacting with the conversion composition, the substrate optionally may be rinsed with tap water, deionized water, reverse osmosis (RO) water and/or an aqueous solution of rinsing agents in order to remove any residue and then optionally may be dried, for example air dried or dried with hot air as described in the preceding sentence.

According to the present invention, at least a portion of the substrate surface may be cleaned and/or deoxidized prior to contacting at least a portion of the substrate surface with the conversion composition described above, in order to remove grease, dirt, and/or other extraneous matter. At least a portion of the surface of the substrate may be cleaned by physical and/or chemical means, such as mechanically abrading the surface and/or cleaning/degreasing the surface with alkaline or acidic cleaning compositions. Such cleaners are often preceded or followed by a water rinse, such as with tap water, distilled water, RO water, or combinations thereof. As used herein, “cleaning compositions” or “cleaner compositions” included in the treatment systems and methods of the present invention may have deoxidizing functionality in addition to degreasing characteristics.

As mentioned above, according to the present invention, the cleaning composition may be alkaline and may have a pH greater than 7, such as greater than 9, such as greater than 11. According the present invention, the pH of the cleaning composition may be 7 to 13, such as 9 to 12.7. In other instances, according to the present invention, the cleaning composition may be acidic and may have a pH less than 7, such as less than 6, such as less than 5.5. According to the present invention, the pH of the cleaning composition may be 0.5 to 6, such as 1.5 to 4.5.

In examples of the present invention, the cleaning composition may include commercially available alkaline cleaners, including Chemkleen™ 163, 177, 611L, 490MX, 2010LP, and 181ALP, Ultrax 32, Ultrax 97, and Ultrax 94D, each of which are commercially available from PPG Industries, Inc. (Cleveland, Ohio), and any of the DFM Series, RECC 1001, and 88X1002 cleaners (commercially available from PRC-DeSoto International, Sylmar, Calif.), and any of the Turco or Bonderite/Ridolene series of cleaners (commercially available from Henkel Technologies, Madison Heights, Mich.), and any of the SOCOCLEAN series of cleaners (commercially available from Socomore).

According to the present invention, the cleaning composition of the present invention may comprise a carrier such as water such that the cleaning composition is in the form of a solution or dispersion. According to the present invention, the solution or dispersion may be brought into contact with the substrate by any of a variety of techniques, including but not limited to dip immersion, spraying, swabbing, or spreading using a brush, roller, or the like. With regard to application via spraying, conventional (automatic or manual) spray techniques and equipment used for air spraying may be used. According to the present invention, the cleaning composition may be applied using an electrolytic-coating system. The dwell time in which the cleaning composition remains in contact with the metal substrate may vary from a few seconds to multiple hours, for example less than 30 minutes or three minutes or less.

When the cleaning composition is applied to the metal substrate by immersion, the immersion times may vary from a few seconds to multiple hours, for example less than 30 minutes or three minutes or less, such as 2 seconds. When the cleaning composition is applied to the metal substrate using a spray application, the composition may be brought into contact with at least a portion of the substrate using conventional spray application methods. The dwell time in which the cleaning composition remains in contact with the metal substrate may vary from a few seconds to multiple hours, for example less than 30 minutes or three minutes or less, such as 2 seconds.

After contacting the metal substrate with the cleaning composition, the metal substrate may optionally be air dried, and then rinsed with tap water, RO water, and/or distilled/de-ionized water. Alternately, after contacting the metal substrate with the composition, the metal substrate may be rinsed with tap water, RO water, and/or distilled/de-ionized water, and then subsequently air dried (if desired). However, the substrate need not be dried, and in some instances, drying is omitted. Additionally, as noted above, the substrate need not be rinsed, and the metal substrate may then be further coated with conversion coatings, primers and/or topcoats to achieve a substrate with a finished coating. Accordingly, in some instances this subsequent rinse may be omitted.

In some instances, according to the present invention, the cleaning composition may be applied to a metal substrate for 1 to 10 minutes (for example, 3 to 5 minutes), and the surface of the metal substrate may be kept wet by reapplying the cleaning composition. Then, the composition is optionally allowed to dry, for example in the absence of heat greater than room temperature, for 5 to 10 minutes (for example, 7 minutes) after the last application of the composition. However, the substrate does not need to be allowed to dry, and in some instances, drying is omitted. For example, according to the present invention, a solvent (e.g., alcohol) may be used to rinse the substrate, which allows the omission of a drying step.

According to the present invention, the metal substrate optionally may be conditioned prior to contacting the metal substrate with the cleaning composition described above. As used herein, the term “conditioning” refers to the surface modification of the substrate prior to subsequent processing. Such surface modification can include various operations, including, but not limited to cleaning (to remove impurities and/or dirt from the surface), deoxidizing, and/or application of a solution or coating, as is known in the art. Conditioning may have one or more benefits, such as the generation of a more uniform starting metal surface, improved adhesion to a subsequent coating on the pre-treated substrate, and/or modification of the starting surface in such a way as to facilitate the deposition of a subsequent composition.

According to the present invention, the metal substrate may be pre-treated by solvent wiping the metal prior to applying the composition to the metal substrate. Nonlimiting examples of suitable solvents include methyl ethyl ketone (MEK), methyl propyl ketone (MPK), acetone, and the like.

According to the present invention, the metal substrate optionally may be prepared by first solvent treating the metal substrate prior to contacting the metal substrate with the cleaning composition. As used herein, the term “solvent treating” refers to rinsing, wiping, spraying, or immersing the substrate in a solvent that assists in the removal of inks, oils, etc. that may be on the metal surface. Alternately, the metal substrate may be prepared by degreasing the metal substrate using conventional degreasing methods prior to contacting the metal substrate with the cleaning composition.

Additional optional procedures for preparing the metal substrate include the use of a surface brightener, such as an acid pickle or light acid etch, or a smut remover.

The metal substrate may be rinsed with either tap water, RO water, and/or distilled/de-ionized water between each of the conversion steps and may be rinsed well with distilled/de-ionized water and/or alcohol after contact with the composition according to the present invention. However, as noted above, according to the present invention, some of the above described pre-treatment procedures and rinses may not be necessary prior to or after application of the cleaning composition.

As mentioned above, according to the present invention, optionally, at least a portion of the cleaned substrate surface may be deoxidized, mechanically and/or chemically. As used herein, the term “deoxidize” means removal of the oxide layer found on the surface of the substrate in order to promote uniform deposition of the conversion composition (described below), as well as to promote the adhesion of the conversion composition coating to the substrate surface. Suitable deoxidizers will be familiar to those skilled in the art. A typical mechanical deoxidizer may be uniform roughening of the substrate surface, such as by using a scouring or cleaning pad. Typical chemical deoxidizers include, for example, acid-based deoxidizers such as phosphoric acid, nitric acid, fluoroboric acid, sulfuric acid, chromic acid, hydrofluoric acid, and ammonium bifluoride, or Amchem 7/17 deoxidizers (available from Henkel Technologies, Madison Heights, Mich.), any of the OAKITE series of deoxidizers (commercially available from BASF), any of the TURCO series of deoxidizers (commercially available from Henkel), any of the Socosurf series of deoxidizers (commercially available from Socomore), or combinations thereof. Often, the chemical deoxidizer comprises a carrier, often an aqueous medium, so that the deoxidizer may be in the form of a solution or dispersion in the carrier, in which case the solution or dispersion may be brought into contact with the substrate by any of a variety of known techniques, such as dipping or immersion, spraying, intermittent spraying, dipping followed by spraying, spraying followed by dipping, brushing, or roll-coating. According to the present invention, the skilled artisan will select a temperature range of the solution or dispersion, when applied to the metal substrate, based on etch rates, for example, at a temperature ranging from 50° F. to 150° F. (10° C. to 66° C.), such as from 70° F. to 130° F. (21° C. to 54° C.), such as from 80° F. to 120° F. (27° C. to 49° C.). The contact time may be from 30 seconds to 20 minutes, such as 1 minute to 15 minutes, such as 90 seconds to 12 minutes, such as 3 minutes to 9 minutes.

As noted above, the system of the present invention may further comprise a sealing composition. The sealing composition may comprise an ammonium-containing compound. The ammonium-containing compound may be in the form of an ammonium salt. Optionally, the sealing composition may further comprise an anion that may be suitable for forming a salt with the ammonium cation, including for example, a sulfate, a nitrate, an acetate, a carbonate, a hydroxide, a phosphate, or combinations thereof. Suitable examples of ammonium-containing compounds include basic salts of ammonium, ammonium zirconium carbonate (AZC), ammonium acetate, ammonium zirconium sulfate, ammonium zirconium lactate, ammonium zirconium glycolate, and the like.

The ammonium of the ammonium-containing compound may be present in the sealing composition in an amount of at least 100 ppm based on total weight of the sealing composition, such as at least 120 ppm, and may be present in the sealing composition in an amount of no more than 1,500 ppm based on total weight of the sealing composition, such as no more than 1,000 ppm. The ammonium may be present in the sealing composition in an amount of 100 ppm to 1,500 ppm based on total weight of the sealing composition, such as 120 ppm to 1,000 ppm.

Optionally, the sealing composition may further comprise a Group IVB metal. The Group IVB metal may, for example, be titanium, zirconium, hafnium or combinations thereof. The Group IVB metal may be introduced to the sealing composition as a compound such as an inorganic or organic salt. Suitable compounds of zirconium include, but are not limited to, hexafluorozirconic acid, alkali metal and ammonium salts thereof, ammonium zirconium carbonate, zirconyl nitrate, zirconyl sulfate, zirconium carboxylates and zirconium hydroxy carboxylates, such as zirconium acetate, zirconium oxalate, ammonium zirconium glycolate, ammonium zirconium lactate, ammonium zirconium citrate and mixtures thereof. A suitable compound of hafnium includes, but is not limited to, hafnium nitrate. A suitable compound of titanium includes, but is not limited to, fluorotitanic acid and its salts.

Nonlimiting examples of anions suitable for forming a salt with the Group IVB metal cation include carbonates, hydroxides, nitrates, halogens, sulfates, phosphates and silicates (e.g., orthosilicates and metasilicates) such that the metal salt may comprise a carbonate, a hydroxide, a nitrate, a halide, a sulfate, a phosphate, a silicate (e.g., orthosilicate or metasilicate), a permanganate, a chromate, a vanadate, a molybdate, and/or a perchlorate.

The Group IVB metal may be present in the sealing composition in an amount of at least 250 ppm based on total weight of the sealing composition, such as at least 500 ppm, and may be present in the sealing composition in an amount of no more than 3,800 ppm based on total weight of the sealing composition, such as no more than 2,600 ppm. The Group IVB metal may be present in the sealing composition in an amount of 250 ppm to 3,800 ppm based on total weight of the sealing composition, such 500 ppm to 2,600 ppm.

According to the present invention, the sealing composition may exclude chromium or chromium-containing compounds. As used herein, the term “chromium-containing compound” refers to materials that include hexavalent chromium. Non-limiting examples of such materials include chromic acid, chromium trioxide, chromic acid anhydride, dichromate salts, such as ammonium dichromate, sodium dichromate, potassium dichromate, and calcium, barium, magnesium, zinc, cadmium, and strontium dichromate. When a sealing composition and/or a coating or a layer, respectively, formed from the same is substantially free, essentially free, or completely free of chromium, this includes chromium in any form, such as, but not limited to, the hexavalent chromium-containing compounds listed above.

Thus, optionally, according to the present invention, the present sealing compositions and/or coatings or layers, respectively, deposited from the same may be substantially free, may be essentially free, and/or may be completely free of one or more of any of the elements or compounds listed in the preceding paragraph. A sealing composition and/or coating or layer, respectively, formed from the same that is substantially free of chromium or derivatives thereof means that chromium or derivatives thereof are not intentionally added, but may be present in trace amounts, such as because of impurities or unavoidable contamination from the environment. In other words, the amount of material is so small that it does not affect the properties of the sealing composition; in the case of chromium, this may further include that the element or compounds thereof are not present in the sealing compositions and/or coatings or layers, respectively, formed from the same in such a level that it causes a burden on the environment. The term “substantially free” means that the sealing compositions and/or coating or layers, respectively, formed from the same contain less than 10 ppm of any or all of the elements or compounds listed in the preceding paragraph, based on total weight of the composition or the layer, respectively, if any at all. The term “essentially free” means that the sealing compositions and/or coatings or layers, respectively, formed from the same contain less than 1 ppm of any or all of the elements or compounds listed in the preceding paragraph, if any at all. The term “completely free” means that the sealing compositions and/or coatings or layers, respectively, formed from the same contain less than 1 ppb of any or all of the elements or compounds listed in the preceding paragraph, if any at all.

According to the present invention, the sealing composition may, in some instances, exclude phosphate ions or phosphate-containing compounds and/or the formation of sludge, such as aluminum phosphate, iron phosphate, and/or zinc phosphate, formed in the case of using a treating agent based on zinc phosphate. As used herein, “phosphate-containing compounds” include compounds containing the element phosphorous such as ortho phosphate, pyrophosphate, metaphosphate, tripolyphosphate, organophosphonates, and the like, and can include, but are not limited to, monovalent, divalent, or trivalent cations such as: sodium, potassium, calcium, zinc, nickel, manganese, aluminum and/or iron. When a composition and/or a layer or coating comprising the same is substantially free, essentially free, or completely free of phosphate, this includes phosphate ions or compounds containing phosphate in any form.

Thus, according to the present invention, sealing composition and/or layers deposited from the same may be substantially free, or in some cases may be essentially free, or in some cases may be completely free, of one or more of any of the ions or compounds listed in the preceding paragraph. A sealing composition and/or layers deposited from the same that is substantially free of phosphate means that phosphate ions or compounds containing phosphate are not intentionally added, but may be present in trace amounts, such as because of impurities or unavoidable contamination from the environment. In other words, the amount of material is so small that it does not affect the properties of the composition; this may further include that phosphate is not present in the sealing compositions and/or layers deposited from the same in such a level that they cause a burden on the environment. The term “substantially free” means that the sealing compositions and/or layers deposited from the same contain less than 5 ppm of any or all of the phosphate anions or compounds listed in the preceding paragraph, based on total weight of the composition or the layer, respectively, if any at all. The term “essentially free” means that the sealing compositions and/or layers comprising the same contain less than 1 ppm of any or all of the phosphate anions or compounds listed in the preceding paragraph. The term “completely free” means that the sealing compositions and/or layers comprising the same contain less than 1 ppb of any or all of the phosphate anions or compounds listed in the preceding paragraph, if any at all.

According to the present invention, the sealing composition may optionally further contain an indicator compound, so named because it indicates, for example, the presence of a chemical species, such as a metal ion, the pH of a composition, and the like. An “indicator”, “indicator compound”, and like terms as used herein refer to a compound that changes color in response to some external stimulus, parameter, or condition, such as the presence of a metal ion, or in response to a specific pH or range of pHs.

The indicator compound used according to the present invention can be any indicator known in the art that indicates the presence of a species, a particular pH, and the like. For example, a suitable indicator may be one that changes color after forming a metal ion complex with a particular metal ion. The metal ion indicator is generally a highly conjugated organic compound. A “conjugated compound” as used herein, and as will be understood by those skilled in the art, refers to a compound having two double bonds separated by a single bond, for example two carbon-carbon double bonds with a single carbon-carbon bond between them. Any conjugated compound can be used according to the present invention.

Similarly, the indicator compound can be one in which the color changes upon change of the pH; for example, the compound may be one color at an acidic or neutral pH and change color in an alkaline pH, or vice versa. Such indicators are well known and widely commercially available. An indicator that “changes color upon transition from a first pH to a second pH” (i.e., from a first pH to a second pH that is more or less acidic or alkaline) therefore has a first color (or is colorless) when exposed to a first pH and changes to a second color (or goes from colorless to colored) upon transition to a second pH (i.e., one that is either more or less acidic or alkaline than the first pH). For example, an indicator that “changes color upon transition to a more alkaline pH (or less acidic pH) goes from a first color/colorless to a second color/color when the pH transitions from acidic/neutral to alkaline. For example, an indicator that “changes color upon transition to a more acidic pH (or less alkaline pH) goes from a first color/colorless to a second color/color when the pH transitions from alkaline/neutral to acidic.

Non-limiting examples of such indicator compounds include methyl orange, xylenol orange, catechol violet, bromophenol blue, green and purple, eriochrome black T, Celestine blue, hematoxylin, calmagite, gallocyanine, and combinations thereof. Optionally, the indicator compound may comprise an organic indicator compound that is a metal ion indicator. Nonlimiting examples of indicator compounds include those found in Table 1. Fluorescent indicators, which will emit light in certain conditions, can also be used according to the present invention, although the use of a fluorescent indicator also may be specifically excluded. That is, alternatively, conjugated compounds that exhibit fluorescence are specifically excluded. As used herein, “fluorescent indicator” and like terms refer to compounds, molecules, pigments, and/or dyes that will fluoresce or otherwise exhibit color upon exposure to ultraviolet or visible light. To “fluoresce” will be understood as emitting light following absorption of shorter wavelength light or other electromagnetic radiation. Examples of such indicators, often referred to as “tags,” include acridine, anthraquinone, coumarin, diphenylmethane, diphenylnaphthylmethane, quinoline, stilbene, triphenylmethane, anthracine and/or molecules containing any of these moieties and/or derivatives of any of these such as rhodamines, phenanthridines, oxazines, fluorones, cyanines and/or acridines.

TABLE 1 CAS Reg. Compound Structure No. Catechol Violet Synonyms: Catecholsulfonphthalein; Pyrocatecholsulfonephthalein; Pyrocatechol Violet

115-41-3 Xylenol Orange Synonym: 3,3′-Bis[N,N- bis(carboxymethyl) aminomethyl]- o-cresolsulfonephthalein tetrasodium salt

3618-43-7

According to the present invention, the conjugated compound useful as indicator may for example comprise catechol violet, as shown in Table 1. Catechol violet (CV) is a sulfone phthalein dye made from condensing two moles of pyrocatechol with one mole of o-sulfobenzoic acid anhydride. It has been found that CV has indicator properties and when incorporated into compositions having metal ions, it forms complexes, making it useful as a complexiometric reagent. As the composition containing the CV chelates metal ions coming from the metal substrate (i.e., those having bi- or higher valence), a generally blue to blue-violet color is observed.

Xylenol orange, as shown in Table 1 may likewise be employed in the compositions according to the present invention. It has been found that xylenol orange has metal ion (i.e., those having bi- or higher valence) indicator properties and when incorporated into compositions having metal ions, it forms complexes, making it useful as a complexiometric reagent. As the composition containing the xylenol orange chelates metal ions, a solution of xylenol orange turns from red to a generally blue color.

According to the present invention, the indicator compound may be present in the sealing composition in an amount of at least 0.01 g/1000 g sealing composition, such as at least 0.05 g/1000 g sealing composition, and in some instances, no more than 3 g/1000 g sealing composition, such as no more than 0.3g/1000 g sealing composition. According to the present invention, the indicator compound may be present in the sealing composition in an amount of 0.01 g/1000 g sealing composition to 3 g/1000 g sealing composition, such as 0.05 g/1000 g sealing composition to 0.3 g/1000 g sealing composition.

According to the present invention, the indicator compound changing color in response to a certain external stimulus provides a benefit when using the sealing composition in that it can serve, for example, as a visual indication that a substrate has been treated with the composition. For example, a sealing composition comprising an indicator that changes color when exposed to a metal ion that is present in the substrate will change color upon complexing with metal ions in that substrate; this allows the user to see that the substrate has been contacted with the composition. Similar benefits can be realized by depositing an alkaline or acid layer on a substrate and contacting the substrate with a composition of the present invention that changes color when exposed to an alkaline or acidic pH.

According to the present invention, the sealing composition may comprise an aqueous medium and optionally may contain other materials such as at least one organic solvent. Nonlimiting examples of suitable such solvents include propylene glycol, ethylene glycol, glycerol, low molecular weight alcohols, and the like. When present, if at all, the organic solvent may be present in the sealing composition in an amount of at least 1 g solvent per liter of sealing composition, such as at least about 2 g solvent per liter of sealing solution, and in some instances, may be present in an amount of no more than 40 g solvent per liter of sealing composition, such as no more than 20 g solvent per liter of sealing solution. According to the present invention, the organic solvent may be present in the sealing composition, if at all, in an amount of 1 g solvent per liter of sealing composition to 40 g solvent per liter of sealing composition, such as 2 g solvent per liter of sealing composition to 20 g solvent per liter of sealing composition.

According to the present invention, the pH of the sealing composition may be at least 5, such as at least 6, such as at least 7, and in some instances may be no higher than 11, such as no higher than 10, such as no higher than 9. According to the present invention, the pH of the sealing composition may be 5 to 11, such as 6 to 10, such as 7 to 9. The pH of the sealing composition may be adjusted using, for example, any acid and/or base as is necessary. According to the present invention, the pH of the sealing composition may be maintained through the inclusion of an acidic material, including carbon dioxide, water soluble and/or water dispersible acids, such as nitric acid, sulfuric acid, and/or phosphoric acid. According to the present invention, the pH of the sealing composition may be maintained through the inclusion of a basic material, including water soluble and/or water dispersible bases, including carbonates such as Group I carbonates, Group II carbonates, hydroxides such as sodium hydroxide, potassium hydroxide, or ammonium hydroxide, ammonia, and/or amines such as triethylamine, methylethyl amine, or mixtures thereof.

As mentioned above, the sealing composition may comprise a carrier, often an aqueous medium, so that the composition is in the form of a solution or dispersion of the ammonium-containing compound in the carrier. According to the present invention, the solution or dispersion may be brought into contact with the substrate by any of a variety of known techniques, such as dipping or immersion, spraying, intermittent spraying, dipping followed by spraying, spraying followed by dipping, brushing, or roll-coating. According to the invention, the solution or dispersion when applied to the metal substrate may be at a temperature ranging from 40° F. to about 160° F., such as 60° F. to 110° F. For example, the process of contacting the metal substrate with the sealing composition may be carried out at ambient or room temperature. The contact time is often from about 1 second to about 15 minutes, such as about 5 seconds to about 2 minutes.

According to the present invention, following the contacting with the sealing composition, the substrate optionally may be air dried at room temperature or may be dried with hot air, for example, by using an air knife, by flashing off the water by brief exposure of the substrate to a high temperature, such as by drying the substrate in an oven at 15° C. to 100° C., such as 20° C. to 90° C., or in a heater assembly using, for example, infrared heat, such as for 10 minutes at 70° C., or by passing the substrate between squeegee rolls. According to the present invention, the substrate surface may be partially, or in some instances, completely dried prior to any subsequent contact of the substrate surface with any water, solutions, compositions, or the like. As used herein with respect to a substrate surface, “completely dry” or “completely dried” means there is no moisture on the substrate surface visible to the human eye.

Optionally, according to the present invention, following the contacting with the sealing composition, the substrate optionally is not rinsed or contacted with any aqueous solutions prior to contacting at least a portion of the substrate surface with subsequent treatment compositions to form films, layers, and/or coatings thereon (described below).

Optionally, according to the present invention, following the contacting with the sealing composition, the substrate optionally may be contacted with tap water, deionized water, RO water and/or any aqueous solution known to those of skill in the art of substrate treatment, wherein such water or aqueous solution may be at a temperature of room temperature (60° F.) to 212° F. The substrate then optionally may be dried, for example air dried or dried with hot air as described in the preceding paragraph such that the substrate surface may be partially, or in some instances, completely dried prior to any subsequent contact of the substrate surface with any water, solutions, compositions, or the like.

According to the present invention, disclosed herein is a method of treating a substrate comprising, or consisting essentially of, or consisting of, contacting at least a portion of the substrate with a conversion composition comprising, or in some instances consisting of, or in some instances consisting essentially of, trivalent chromium; and contacting the surface contacted with the conversion composition with a sealing composition comprising, or consisting essentially of, or consisting of, an ammonium-containing compound.

It has been surprisingly discovered that corrosion performance was improved (i.e., the number of pits was reduced by at least 10%, such as at least 20%, such as at least 25%, such as at least 50%) when a substrate was treated with a trivalent chromium-containing composition of the present invention followed by an ammonium-containing sealing composition of the present invention compared to a substrate treated with a trivalent chromium-containing composition followed by sealing composition that does not contain an ammonium-containing compound. These results were unexpected.

It also has been surprisingly discovered that substrate surfaces treated with a system or method of the present invention may have a fluoride content of less than 7 atomic percent at the air-surface interface as measured by XPS depth profiling (using a Physical Electronics VersaProbe II instrument equipped with a monochromatic Al kα x-ray source (hv=1,486.7 eV) and a concentric hemispherical analyzer), such as less than 6 atomic percent, such as less than 5 atomic percent, such as less than 4 atomic percent, such as less than 3 atomic percent, such as less than 2 atomic percent, such as less than 1 atomic percent.

It also has been surprisingly discovered that substrates treated with a system or method of the present invention may have a fluoride content of less than 4.5 atomic percent at 50 nm to 100 nm below the air-surface interface as measured by XPS depth profiling (using a Physical Electronics VersaProbe II instrument equipped with a monochromic Al kα x-ray source (hv=1,486.7 eV) and a concentric hemispherical analyzer), such as less than 4 atomic percent, such as less than 3.5 atomic percent, such as less than 3 atomic percent, such as less than 2.5 atomic percent, such as less than 2 atomic percent, such as less than 1.5 atomic percent, such as less than 1 atomic percent.

It also has been surprisingly discovered that substrates treated with a system or method of the present invention may have a fluoride that is reduced by at least 30% at the air-surface interface up to 150 nm below the air-surface interface compared to a substrate treated with the conversion composition and a sealing composition that does not contain an ammonium-containing compound as measured by XPS depth profiling (using a Physical Electronics VersaProbe II instrument equipped with a monochromatic Al kα x-ray source (hv=1,486.7 eV) and a concentric hemispherical analyzer), such as reduced by at least 40%, such as reduced by at least 50%, such as reduced by at least 60%, such as reduced by at least 70%, such as reduced by at least 80%, such as reduced by at least 90%.

Also surprisingly discovered was a substrate comprising a surface having a fluoride content of less than 7 atomic percent at the air-surface interface as measured by XPS depth profiling (using a Physical Electronics VersaProbe II instrument equipped with a monochromatic Al kα x-ray source (hv=1,486.7 eV) and a concentric hemispherical analyzer), such as less than 6 atomic percent, such as less than 5 atomic percent, such as less than 4 atomic percent, such as less than 3 atomic percent, such as less than 2 atomic percent, such as less than 1 atomic percent.

Also surprisingly discovered was a substrate having a fluoride content of less than 4.5 atomic percent 50 nm to 100 nm below the air-surface interface as measured by XPS depth profiling (using a Physical Electronics VersaProbe II instrument equipped with a monochromatic Al kα x-ray source (hv=1,486.7 eV) and a concentric hemispherical analyzer), such as less than 4 atomic percent, such as less than 3.5 atomic percent, such as less than 3 atomic percent, such as less than 2 atomic percent, such as less than 1 atomic percent.

According to the present invention, after the substrate is contacted with the sealing composition, a coating composition comprising a film-forming resin may be deposited onto at least a portion of the surface of the substrate that has been contacted with the sealing composition. Any suitable technique may be used to deposit such a coating composition onto the substrate, including, for example, brushing, dipping, flow coating, spraying and the like. In some instances, however, as described in more detail below, such depositing of a coating composition may comprise an electrocoating step wherein an electrodepositable composition is deposited onto a metal substrate by electrodeposition. In certain other instances, as described in more detail below, such depositing of a coating composition may comprise a powder coating step. In still other instances, the coating composition may be a liquid coating composition.

According to the present invention, the coating composition may comprise a thermosetting film-forming resin or a thermoplastic film-forming resin. As used herein, the term “film-forming resin” refers to resins that can form a self-supporting continuous film on at least a horizontal surface of a substrate upon removal of any diluents or carriers present in the composition or upon curing at ambient or elevated temperature. Conventional film-forming resins that may be used include, without limitation, those typically used in automotive OEM coating compositions, automotive refinish coating compositions, industrial coating compositions, architectural coating compositions, coil coating compositions, and aerospace coating compositions, among others. As used herein, the term “thermosetting” refers to resins that “set” irreversibly upon curing or crosslinking, wherein the polymer chains of the polymeric components are joined together by covalent bonds. This property is usually associated with a cross-linking reaction of the composition constituents often induced, for example, by heat or radiation. Curing or crosslinking reactions also may be carried out under ambient conditions. Once cured or crosslinked, a thermosetting resin will not melt upon the application of heat and is insoluble in solvents. As used herein, the term “thermoplastic” refers to resins that comprise polymeric components that are not joined by covalent bonds and thereby can undergo liquid flow upon heating and are soluble in solvents.

As previously indicated, according to the present invention, an electrodepositable coating composition comprising a water-dispersible, ionic salt group-containing film-forming resin that may be deposited onto the substrate by an electrocoating step wherein the electrodepositable coating composition is deposited onto the metal substrate by electrodeposition.

The ionic salt group-containing film-forming polymer may comprise a cationic salt group containing film-forming polymer for use in a cationic electrodepositable coating composition. As used herein, the term “cationic salt group-containing film-forming polymer” refers to polymers that include at least partially neutralized cationic groups, such as sulfonium groups and ammonium groups, that impart a positive charge. The cationic salt group-containing film-forming polymer may comprise active hydrogen functional groups, including, for example, hydroxyl groups, primary or secondary amine groups, and thiol groups. Cationic salt group-containing film-forming polymers that comprise active hydrogen functional groups may be referred to as active hydrogen-containing, cationic salt group-containing film-forming polymers. Examples of polymers that are suitable for use as the cationic salt group-containing film-forming polymer include, but are not limited to, alkyd polymers, acrylics, polyepoxides, polyamides, polyurethanes, polyureas, polyethers, and polyesters, among others.

The cationic salt group-containing film-forming polymer may be present in the cationic electrodepositable coating composition in an amount of 40% to 90% by weight, such as 50% to 80% by weight, such as 60% to 75% by weight, based on the total weight of the resin solids of the electrodepositable coating composition. As used herein, the “resin solids” include the ionic salt group-containing film-forming polymer, curing agent, and any additional water-dispersible non-pigmented component(s) present in the electrodepositable coating composition.

Alternatively, the ionic salt group containing film-forming polymer may comprise an anionic salt group containing film-forming polymer for use in an anionic electrodepositable coating composition. As used herein, the term “anionic salt group containing film-forming polymer” refers to an anionic polymer comprising at least partially neutralized anionic functional groups, such as carboxylic acid and phosphoric acid groups that impart a negative charge. The anionic salt group-containing film-forming polymer may comprise active hydrogen functional groups. Anionic salt group-containing film-forming polymers that comprise active hydrogen functional groups may be referred to as active hydrogen-containing, anionic salt group-containing film-forming polymers.

The anionic salt group-containing film-forming polymer may comprise base-solubilized, carboxylic acid group-containing film-forming polymers such as the reaction product or adduct of a drying oil or semi-drying fatty acid ester with a dicarboxylic acid or anhydride; and the reaction product of a fatty acid ester, unsaturated acid or anhydride and any additional unsaturated modifying materials which are further reacted with polyol. Also suitable are the at least partially neutralized interpolymers of hydroxy-alkyl esters of unsaturated carboxylic acids, unsaturated carboxylic acid and at least one other ethylenically unsaturated monomer. Still another suitable anionic electrodepositable resin comprises an alkyd-aminoplast vehicle, i.e., a vehicle containing an alkyd resin and an amine-aldehyde resin. Another suitable anionic electrodepositable resin composition comprises mixed esters of a resinous polyol. Other acid functional polymers may also be used such as phosphatized polyepoxide or phosphatized acrylic polymers. Exemplary phosphatized polyepoxides are disclosed in U.S. Patent Application Publication No. 2009-0045071 at [0004]-[0015] and U.S. patent application Ser. No. 13/232,093 at [0014]-[0040], the cited portions of which being incorporated herein by reference.

The anionic salt group-containing film-forming polymer may be present in the anionic electrodepositable coating composition in an amount 50% to 90%, such as 55% to 80%, such as 60% to 75%, based on the total weight of the resin solids of the electrodepositable coating composition.

The electrodepositable coating composition may further comprise a curing agent. The curing agent may react with the reactive groups, such as active hydrogen groups, of the ionic salt group-containing film-forming polymer to effectuate cure of the coating composition to form a coating. Non-limiting examples of suitable curing agents are at least partially blocked polyisocyanates, aminoplast resins and phenoplast resins, such as phenolformaldehyde condensates including allyl ether derivatives thereof.

The curing agent may be present in the cationic electrodepositable coating composition in an amount of 10% to 60% by weight, such as 20% to 50% by weight, such as 25% to 40% by weight, based on the total weight of the resin solids of the electrodepositable coating composition. Alternatively, the curing agent may be present in the anionic electrodepositable coating composition in an amount of 10% to 50% by weight, such as 20% to 45% by weight, such as 25% to 40% by weight, based on the total weight of the resin solids of the electrodepositable coating composition.

The electrodepositable coating composition may further comprise other optional ingredients, such as a pigment composition and, if desired, various additives such as fillers, plasticizers, anti-oxidants, biocides, UV light absorbers and stabilizers, hindered amine light stabilizers, defoamers, fungicides, dispersing aids, flow control agents, surfactants, wetting agents, or combinations thereof.

The electrodepositable coating composition may comprise water and/or one or more organic solvent(s). Water can for example be present in amounts of 40% to 90% by weight, such as 50% to 75% by weight, based on total weight of the electrodepositable coating composition. If used, the organic solvents may typically be present in an amount of less than 10% by weight, such as less than 5% by weight, based on total weight of the electrodepositable coating composition. The electrodepositable coating composition may in particular be provided in the form of an aqueous dispersion. The total solids content of the electrodepositable coating composition may be from 1% to 50% by weight, such as 5% to 40% by weight, such as 5% to 20% by weight, based on the total weight of the electrodepositable coating composition. As used herein, “total solids” refers to the non-volatile content of the electrodepositable coating composition, i.e., materials which will not volatilize when heated to 110° C. for 15 minutes.

The cationic electrodepositable coating composition may be deposited upon an electrically conductive substrate by placing the composition in contact with an electrically conductive cathode and an electrically conductive anode, with the surface to be coated being the cathode. Alternatively, the anionic electrodepositable coating composition may be deposited upon an electrically conductive substrate by placing the composition in contact with an electrically conductive cathode and an electrically conductive anode, with the surface to be coated being the anode. An adherent film of the electrodepositable coating composition is deposited in a substantially continuous manner on the cathode or anode, respectively, when a sufficient voltage is impressed between the electrodes. The applied voltage may be varied and can be, for example, as low as one volt to as high as several thousand volts, such as between 50 and 500 volts. Current density is usually between 1.0 ampere and 15 amperes per square foot (10.8 to 161.5 amperes per square meter) and tends to decrease quickly during the electrodeposition process, indicating formation of a continuous self-insulating film.

Once the cationic or anionic electrodepositable coating composition is electrodeposited over at least a portion of the electroconductive substrate, the coated substrate is heated to a temperature and for a time sufficient to cure the electrodeposited coating on the substrate. For cationic electrodeposition, the coated substrate may be heated to a temperature ranging from 250° F. to 450° F. (121.1° C. to 232.2° C.), such as from 275° F. to 400° F. (135° C. to 204.4° C.), such as from 300° F. to 360° F. (149° C. to 180° C.). For anionic electrodeposition, the coated substrate may be heated to a temperature ranging from 180° F. to 450° F. (82.2° C. to 232.2° C.), such as from 275° F. to 400° F. (135° C. to 204.4° C.), such as from 300° F. to 360° F. (149° C. to 180° C.), such as 200° F. to 210.2° F. (93° C. to 99° C.). The curing time may be dependent upon the curing temperature as well as other variables, for example, the film thickness of the electrodeposited coating, level and type of catalyst present in the composition and the like. For example, the curing time can range from 10 minutes to 60 minutes, such as 20 to 40 minutes. The thickness of the resultant cured electrodeposited coating may range from 2 to 50 microns.

Alternatively, as mentioned above, according to the present invention, after the substrate has been contacted with the sealing composition, a powder coating composition may then be deposited onto at least a portion of the surface of the substrate. As used herein, “powder coating composition” refers to a coating composition which is completely free of water and/or solvent. Accordingly, the powder coating composition disclosed herein is not synonymous to waterborne and/or solvent-borne coating compositions known in the art.

According to the present invention, the powder coating composition may comprise (a) a film forming polymer having a reactive functional group; and (b) a curing agent that is reactive with the functional group. Examples of powder coating compositions that may be used in the present invention include the polyester-based ENVIROCRON line of powder coating compositions (commercially available from PPG Industries, Inc.) or epoxy-polyester hybrid powder coating compositions. Alternative examples of powder coating compositions that may be used in the present invention include low temperature cure thermosetting powder coating compositions comprising (a) at least one tertiary aminourea compound, at least one tertiary aminourethane compound, or mixtures thereof, and (b) at least one film-forming epoxy-containing resin and/or at least one siloxane-containing resin (such as those described in U.S. Pat. No. 7,470,752, assigned to PPG Industries, Inc. and incorporated herein by reference); curable powder coating compositions generally comprising (a) at least one tertiary aminourea compound, at least one tertiary aminourethane compound, or mixtures thereof, and (b) at least one film-forming epoxy-containing resin and/or at least one siloxane-containing resin (such as those described in U.S. Pat. No. 7,432,333, assigned to PPG Industries, Inc. and incorporated herein by reference); and those ccomprising a solid particulate mixture of a reactive group-containing polymer having a T_(g) of at least 30° C. (such as those described in U.S. Pat. No. 6,797,387, assigned to PPG Industries, Inc. and incorporated herein by reference). As used herein, the term “glass transition temperature” or “Tg” is a theoretical value being the glass transition temperature as calculated by the method of Fox on the basis of monomer composition of the monomer charges according to T. G. Fox, Bull. Am. Phys. Soc. (Se. II)1, 123 (1056) and J. Bandrup, E. H. Immergut, Polymer Handbook 3^(rd) edition, John Wiley, New York, 1989.

After deposition of the powder coating composition, the coating is often heated to cure the deposited composition. The heating or curing operation is often carried out at a temperature in the range of from 150° C. to 200° C., such as from 170° C. to 190° C., for a period of time ranging from 10 to 20 minutes. According to the invention, the thickness of the resultant film is from 50 microns to 125 microns.

As mentioned above, according to the present invention, the coating composition may be a liquid coating composition. As used herein, “liquid coating composition” refers to a coating composition which contains a portion of water and/or organic solvent. Accordingly, the liquid coating composition disclosed herein is synonymous to waterborne and/or solvent-borne coating compositions known in the art.

According to the present invention, the liquid coating composition may comprise, for example, (a) a film forming polymer having a reactive functional group; and (b) a curing agent that is reactive with the functional group. In other examples, the liquid coating may contain a film forming polymer that may react with oxygen in the air or coalesce into a film with the evaporation of water and/or solvents. These film forming mechanisms may require or be accelerated by the application of heat or some type of radiation such as Ultraviolet or Infrared. Examples of liquid coating compositions that may be used in the present invention include the SPECTRACRON® line of solvent-based coating compositions, the AQUACRON® line of water-based coating compositions, and the RAYCRON® line of UV cured coatings (all commercially available from PPG Industries, Inc.).

Suitable film forming polymers that may be used in the liquid coating composition of the present invention may comprise a (poly)ester, an alkyd, a (poly)urethane, an isocyanate, a (poly)urea, a (poly)epoxy, an anhydride, an acrylic, a (poly)ether, a (poly)sulfide, a (poly)amine, a (poly)amide, (poly)vinyl chloride, (poly)olefin, (poly)vinylidene fluoride, (poly)siloxane, or combinations thereof.

According to the present invention, the substrate that has been contacted with the sealing composition may also be contacted with a primer composition and/or a topcoat composition. The primer coat may be, for examples, chromate-based primers and advanced performance topcoats. According to the present invention, the primer coat can be a conventional chromate based primer coat, such as those available from PPG Industries, Inc. (product code 44GN072), or a chrome-free primer such as those available from PPG (DESOPRIME CA7502, DESOPRIME CA7521, Deft 02GN083, Deft 02GN084). Alternately, the primer coat can be a chromate-free primer coat, such as the coating compositions described in U.S. patent application Ser. No. 10/758,973, titled “CORROSION RESISTANT COATINGS CONTAINING CARBON”, and U.S. patent application Ser. Nos. 10/758,972, and 10/758,972, both titled “CORROSION RESISTANT COATINGS”, all of which are incorporated herein by reference, and other chrome-free primers that are known in the art, and which can pass the military requirement of MIL-PRF-85582 Class N or MIL-PRF-23377 Class N may also be used with the current invention.

As mentioned above, the substrate of the present invention also may comprise a topcoat. As used herein, the term “topcoat” refers to a mixture of binder(s) which can be an organic or inorganic based polymer or a blend of polymers, and typically at least one pigment, which can optionally contain at least one solvent or mixture of solvents, and can optionally contain at least one curing agent. A topcoat is typically the coating layer in a single or multi-layer coating system whose outer surface is exposed to the atmosphere or environment, and its inner surface is in contact with another coating layer or polymeric substrate. Examples of suitable topcoats include those conforming to MIL-PRF-85285D, such as those available from PPG (Deft 03W127A and Deft 03GY292). According to the present invention, the topcoat may be an advanced performance topcoat, such as those available from PPG (Defthane® ELT™ 99GY001 and 99W009). However, other topcoats and advanced performance topcoats can be used in the present invention as will be understood by those of skill in the art with reference to this disclosure.

According to the present invention, the metal substrate also may comprise a self-priming topcoat, or an enhanced self-priming topcoat. The term “self-priming topcoat”, also referred to as a “direct to substrate” or “direct to metal” coating, refers to a mixture of a binder(s), which can be an organic or inorganic based polymer or blend of polymers, and typically at least one pigment, which can optionally contain at least one solvent or mixture of solvents, and can optionally contain at least one curing agent. The term “enhanced self-priming topcoat”, also referred to as an “enhanced direct to substrate coating” refers to a mixture of functionalized fluorinated binders, such as a fluoroethylene-alkyl vinyl ether in whole or in part with other binder(s), which can be an organic or inorganic based polymer or blend of polymers, and typically at least one pigment, which can optionally contain at least one solvent or mixture of solvents, and can optionally contain at least one curing agent. Examples of self-priming topcoats include those that conform to TT-P-2756A. Examples of self-priming topcoats include those available from PPG (03W169 and 03GY369), and examples of enhanced self-priming topcoats include Defthane® ELT™/ESPT and product code number 97GY121, available from PPG. However, other self-priming topcoats and enhanced self-priming topcoats can be used in the coating system according to the present invention as will be understood by those of skill in the art with reference to this disclosure.

According to the present invention, the self-priming topcoat and/or enhanced self-priming topcoat may be applied directly to the sealed substrate. The self-priming topcoat and enhanced self-priming topcoat can optionally be applied to an organic or inorganic polymeric coating, such as a primer or paint film. The self-priming topcoat layer and enhanced self-priming topcoat is typically the coating layer in a single or multi-layer coating system where the outer surface of the coating is exposed to the atmosphere or environment, and the inner surface of the coating is typically in contact with the substrate or optional polymer coating or primer.

According to the present invention, the topcoat, self-priming topcoat, and enhanced self-priming topcoat can be applied to the sealed substrate, in either a wet or “not fully cured” condition that dries or cures over time, that is, solvent evaporates and/or there is a chemical reaction. The coatings can dry or cure either naturally or by accelerated means for example, an ultraviolet light cured system to form a film or “cured” paint. The coatings can also be applied in a semi or fully cured state, such as an adhesive.

In addition, a colorant and, if desired, various additives such as surfactants, wetting agents or catalyst can be included in the coating composition (electrodepositable, powder, or liquid). As used herein, the term “colorant” means any substance that imparts color and/or other opacity and/or other visual effect to the composition. Example colorants include pigments, dyes and tints, such as those used in the paint industry and/or listed in the Dry Color Manufacturers Association (DCMA), as well as special effect compositions.

In general, the colorant can be present in the coating composition in any amount sufficient to impart the desired visual and/or color effect. The colorant may comprise from 1 to 65 weight percent, such as from 3 to 40 weight percent or 5 to 35 weight percent, with weight percent based on the total weight of the composition.

EXAMPLES

TABLE 2 Materials Bonderite C-AK 6849 (known as Turco 6849) Henkel Corp. Bonderite C-AK 4215 NC-LT Aero Henkel Corp. (known as Turco 4215 NC-LT) Bonderite C-IC Smutgo NC Aero Henkel Corp. (known as Turco Liquid Smut-Go NC) Socosurf A1806 Socomore Socosurf A1858 Socomore Potassium Hexafluorozirconate Sigma Aldrich Chromium (III) Potassium Sulfate Sigma Aldrich dodecahydrate, ≥ 98% Ammonium Zirconium Carbonate solution* Luxfer MEL Technologies Ammonium Carbonate Acros Organics Ammonium Acetate Sigma Aldrich Lithium carbonate, 99% Alfa Aesar Sodium molybdenum oxide dehydrate, 98% Alfa Aesar *includes ZrO₂ + HfO₂ content in a total amount of 19.9% as per manufacturer’s COA

Cleaner Solutions

TABLE 3 Example A Material Volume (mL) Turco 6849 2160 Tap water 8640

TABLE 4 Example B Material Volume (mL) Turco 4215NC-LT 600 Deionized water 12200 Cleaner Compositions A and B were prepared per manufacturers' instructions.

Deoxidizers

TABLE 5 Example C Material Volume (mL) SmutGo NC 2160 Deionized water 8640

TABLE 6 Example D Material Volume (mL) Socosurf A1806 1312 Socosurf A1858 5000 Deionized water 6188 Deoxidizer Compositions C and D were prepared per manufacturer's instructions.

TABLE 7 Trivalent Chromium Formulation Chromium (III) Potassium Potassium Hexafluorozirconate Deionized Sulfate (g) (g) Water (g) Example E 19.0 11.40 7565.6

Composition E was prepared by first dissolving the chromium salt in approximately half of the water under mild mechanical stirring, without heat, using a ceramic stirring hotplate (VWR catalogue number 97042-642). Then, the zirconium salt was dissolved in the balance of the water in a separate beaker under mild mechanical stirring, without heat, using the ceramic stirring hotplate. The solution was then blended and left to sit for a minimum of 5 days before use.

Sealing Compositions

TABLE 8 Example F Mass (g) Lithium Carbonate 4.6 Sodium Molybdate 5.0 Deionized Water 2990.4

Sealing Composition F was prepared by dissolving the lithium carbonate in the entirety of water under mild mechanical stirring, without heat, using a ceramic stirring hotplate (VWR catalogue number 97042-642). Next the molybdenum salt was added to the lithium carbonate solution and stirred, without heat, using a ceramic stirring hotplate (VWR catalogue number 97042-642).

TABLE 9 Example G Mass (g) Ammonium Zirconium Carbonate 29.00 Deionized Water 3691.00

TABLE 10 Example H Mass (g) Ammonium Carbonate, 0.05% 0.50 Deionized Water 922.75

TABLE 11 Example I Mass (g) Ammonium Acetate 0.50 Deionized Water 922.75

Sealing Compositions G to H were prepared by dissolving the salt in water under mild mechanical stirring, without heat, using a ceramic stirring hotplate (VWR catalogue number 97042-642).

Comparative Examples Example 1

Two aluminum 2024T3 bare substrates (Bralco Metals, Wichita Kans.) measuring 3″×5″×0.032″ were hand-wiped with methyl ethyl ketone (100%) and a disposable cloth and allowed to air dry prior to chemical cleaning. The panels were immersed in the cleaner solution of Example A for 5 minutes at 130° F. with mild agitation. The panels were then immersed in a tap water rinse for 2.5 minutes at 110° F. with mild agitation followed by a second tap water immersion rinse for 2.5 minutes at 110° F. with mild agitation. The panels were then rinsed with a gentle deionized water spray for 5 seconds. The panels were immersed in a deoxidizing solution of Example C for 5 minutes at ambient temperature followed by a tap water immersion rinse for 1 minute at ambient temperature with mild agitation followed by a second immersion in tap water rinse for 1 minutes at ambient temperature with mild agitation. The panels were then rinsed with a gentle deionized water spray for 5 seconds. The panels were then placed in the conversion bath solution of Example E for 6 minutes at ambient temperature with mild agitation followed by a deionized water immersion rinse for 2 minutes at ambient temperature with mild agitation followed by a second immersion in deionized water rinse for 2 minutes at ambient temperature with mild agitation. The panels were then rinsed with a gentle deionized water spray for 5 seconds.

The panels were left to dry for a minimum of 18 hours at ambient conditions. One panel was placed in a neutral salt spray cabinet operated according to modified ASTM B117 for 14 day corrosion testing (modified to check operating conditions of the salt spray cabinet weekly rather than daily). Corrosion performance was evaluated by counting the number of pits visible to the naked eye on the panel. Data are reported in Table 12.

A second panel was analyzed to determine the concentration of the elements shown at various depths using XPS depth profiling. Data are shown in FIG. 1 . The XPS depth profile of the substrates was generated using a Physical Electronics VersaProbe II instrument equipped with a monochromatic Al kα x-ray source (hv=1,486.7 eV) and a concentric hemispherical analyzer. Charge neutralization was performed using both low energy electrons (<5 eV) and argon ions. The binding energy axis was calibrated using sputter cleaned Cu (Cu 2p3/2=932.62 eV, Cu 3p_(3/2)=75.1 eV) and Au foils (Au 4f_(7/2)=83.96 eV). Peaks were charge referenced to CHx band in the carbon is spectra at 284.8 eV. Measurements were made at a takeoff angle of 45° with respect to the sample surface plane. This resulted in a typical sampling depth of 3-6 nm (95% of the signal originated from this depth or shallower). Quantification was done using instrumental relative sensitivity factors (RSFs) that account for the x-ray cross section and inelastic mean free path of the electrons. Depth profiling was done using a 4 kV Ar+ beam rastered over a 3 mm×3 mm area. The samples were rotated during profiling to minimize any roughening. The sputtering rate for SiO2 under these conditions was 14.2 nm/min.

Example 2

Aluminum 2024T3 bare substrate (Bralco Metals, Wichita Kans.) measuring 3″×5″×0.032″ was hand-wiped with methyl ethyl ketone (100%) and a disposable cloth and allowed to air dry prior to chemical cleaning. The panel was immersed in the cleaner solution of Example B for 10 minutes at 140° F. with mild agitation. The panel was then immersed in a tap water rinse for 5 minutes at 104° F. with mild agitation followed by a second tap water immersion rinse for 2 minutes at 104° F. with mild agitation. The panel was then rinsed with a gentle deionized water spray for 5 seconds. The panel was immersed in a deoxidizing solution of Example D for 7 minutes at 81° F. with mild agitation followed by a tap water immersion rinse for 5 minutes at 81° F. with mild agitation followed by a second tap water immersion rinse for 2 minutes at 81° F. with mild agitation. The panel was then rinsed with a gentle deionized water spray for 5 seconds. The panel was then placed in the conversion bath solution of Example E for 6 minutes at ambient temperature with mild agitation followed by a deionized water immersion rinse for 5 minutes at 77° F. with mild agitation followed by a second immersion rinse in deionized water for 5 minutes at ambient temperature. The panel was then rinsed with a gentle deionized water spray for 5 seconds.

The panel was left to dry for a minimum of 18 hours at ambient conditions before being placed in a neutral salt spray cabinet operated according to ASTM B117 for 14 day corrosion testing. Corrosion performance was evaluated by counting the number of pits visible to the naked eye on the panel. Data are reported in Table 12.

Example 3

Aluminum 2024T3 bare substrate (Bralco Metals, Wichita Kans.) measuring 3″×5″×0.032″ was hand-wiped with methyl ethyl ketone (100%) and a disposable cloth and allowed to air dry prior to chemical cleaning. The panel was immersed in the cleaner solution of Example A for 5 minutes at 130° F. with mild agitation. The panel was then immersed in a tap water rinse for 2.5 minutes at 110° F. with mild agitation followed by a second tap water immersion rinse for 2.5 minutes at 110° F. with mild agitation. The panel was then rinsed with a gentle deionized water spray for 5 seconds. The panel was immersed in a deoxidizing solution of Example C for 5 minutes at ambient temperature followed by a tap water immersion rinse for 1 minute at ambient temperature with mild agitation followed by a second immersion in tap water rinse for 1 minutes at ambient temperature with mild agitation. The panel was then rinsed with a gentle deionized water spray for 5 seconds. The panel was then placed in the conversion bath solution of Example E for 6 minutes at ambient temperature with mild agitation followed by a deionized water immersion rinse for 2 minutes at ambient temperature with mild agitation followed by a second immersion in deionized water rinse for 2 minutes at ambient temperature with mild agitation. The panel was then rinsed with a gentle deionized water spray for 5 seconds. The panel was then immersed in the seal solution of Example F for 2 minutes at ambient temperature with intermittent agitation.

The panel was left to dry for a minimum of 18 hours at ambient conditions before being placed in a neutral salt spray cabinet operated according to ASTM B117 for 14 day corrosion testing. Corrosion performance was evaluated by counting the number of pits visible to the naked eye on the panel. Data are reported in Table 12.

Experimental Examples Example 4

Two aluminum 2024T3 bare substrates (Bralco Metals, Wichita Kans.) measuring 3″×5″×0.032″ were hand-wiped with methyl ethyl ketone (100%) and a disposable cloth and allowed to air dry prior to chemical cleaning. The panels were immersed in the cleaner solution of Example A for 5 minutes at 130° F. with mild agitation. The panels were then immersed in a tap water rinse for 2.5 minutes at 110° F. with mild agitation followed by a second tap water immersion rinse for 2.5 minutes at 110° F. with mild agitation. The panels were then rinsed with a gentle deionized water spray for 5 seconds. The panels were immersed in a deoxidizing solution of Example C for 5 minutes at ambient temperature followed by a tap water immersion rinse for 1 minute at ambient temperature with mild agitation followed by a second immersion in tap water rinse for 1 minutes at ambient temperature with mild agitation. The panels were then rinsed with a gentle deionized water spray for 5 seconds. The panels were then placed in the conversion bath solution of Example E for 6 minutes at ambient temperature with mild agitation followed by a deionized water immersion rinse for 2 minutes at ambient temperature with mild agitation followed by a second immersion in deionized water rinse for 2 minutes at ambient temperature with mild agitation. The panels were then rinsed with a gentle deionized water spray for 5 seconds. After, the panels were immersed in the seal solution of Example G for 1 minute at ambient temperature with intermittent agitation. The panels were then rinsed with a gentle deionized water spray for 5 seconds.

The panels were left to dry for a minimum of 18 hours at ambient conditions. One panel was placed in a neutral salt spray cabinet operated according to ASTM B117 for 14 day corrosion testing. Corrosion performance was evaluated by counting the number of pits visible to the naked eye on the panel. Data are reported in Table 12.

The second panel was analyzed to determine the concentration of the elements shown at various depths using XPS depth profiling as described in Example 1. Data are shown in FIG. 1 .

Example 5

Aluminum 2024T3 bare substrate (Bralco Metals, Wichita Kans.) measuring 3″×5″×0.032″ was hand-wiped with methyl ethyl ketone (100%) and a disposable cloth and allowed to air dry prior to chemical cleaning. The panel was immersed in the cleaner solution of Example B for 10 minutes at 140° F. with mild agitation. The panel was then immersed in a tap water rinse for 5 minutes at 104° F. with mild agitation followed by a second tap water immersion rinse for 2 minutes at 104° F. with mild agitation. The panel was then rinsed with a gentle deionized water spray for 5 seconds. The panel was immersed in a deoxidizing solution of Example D for 7 minutes at 81° F. with mild agitation followed by a tap water immersion rinse for 5 minutes at 81° F. with mild agitation followed by a second tap water immersion rinse for 2 minutes at 81° F. with mild agitation. The panel was then rinsed with a gentle deionized water spray for 5 seconds. The panel was then placed in the conversion bath solution of Example E for 6 minutes at ambient temperature with mild agitation followed by a deionized water immersion rinse for 5 minutes at 77° F. with mild agitation followed by a second immersion rinse in deionized water for 5 minutes at ambient temperature. The panel was then rinsed with a gentle deionized water spray for 5 seconds. After, the panel was immersed in the seal solution of Example G for 1 minute at ambient temperature with intermittent agitation. The panel was then rinsed with a gentle deionized water spray for 5 seconds.

The panel was left to dry for a minimum of 18 hours at ambient conditions before being placed in a neutral salt spray cabinet operated according to ASTM B117 for 14 day corrosion testing. Corrosion performance was evaluated by counting the number of pits visible to the naked eye on the panel. Data are reported in Table 12.

Example 6

Aluminum 2024T3 bare substrate (Bralco Metals, Wichita Kans.) measuring 3″×5″×0.032″ was hand-wiped with methyl ethyl ketone (100%) and a disposable cloth and allowed to air dry prior to chemical cleaning. The panel was immersed in the cleaner solution of Example A for 10 minutes at 140° F. with mild agitation. The panel was then immersed in a tap water rinse for 5 minutes at 104° F. with mild agitation followed by a second tap water immersion rinse for 2 minutes at 104° F. with mild agitation. The panel was then rinsed with a gentle deionized water spray for 5 seconds. Next the panel was rinsed with a gentle deionized water spray for 5 seconds. The panel was immersed in a deoxidizing solution of Example C for 5 minutes at ambient temperature followed by a tap water immersion rinse for 5 minutes at 81° F. with mild agitation followed by a second immersion in tap water rinse for 2 minutes at 104° F. with mild agitation. The panel was then rinsed with a gentle deionized water spray for 5 seconds. The panel was then placed in the conversion bath solution of Example E for 6 minutes at ambient temperature with mild agitation followed by a deionized water immersion rinse for 5 minutes at 77° F. with mild agitation followed by a second immersion rinse in deionized water for 5 minutes at ambient temperature. The panel was then rinsed with a gentle deionized water spray for 5 seconds. After, the panel was immersed in the seal solution of Example H for 1 minute at ambient temperature with intermittent agitation. The panel was then rinsed with a gentle deionized water spray for 5 seconds.

The panel was left to dry for a minimum of 18 hours at ambient conditions before being placed in a neutral salt spray cabinet operated according to ASTM B117 for 14 day corrosion testing. Corrosion performance was evaluated by counting the number of pits visible to the naked eye on the panel. Data are reported in Table 12.

Example 7

Aluminum 2024T3 bare substrate (Bralco Metals, Wichita Kans.) measuring 3″×5″×0.032″ was hand-wiped with methyl ethyl ketone (100%) and a disposable cloth and allowed to air dry prior to chemical cleaning. The panel was immersed in the cleaner solution of Example A for 10 minutes at 140° F. with mild agitation. The panel was then immersed in a tap water rinse for 5 minutes at 104° F. with mild agitation followed by a second tap water immersion rinse for 2 minutes at 104° F. with mild agitation. The panel was then rinsed with a gentle deionized water spray for 5 seconds. Next the panel was rinsed with a gentle deionized water spray for 5 seconds. The panel was immersed in a deoxidizing solution of Example C for 5 minutes at ambient temperature followed by a tap water immersion rinse for 5 minutes at 81° F. with mild agitation followed by a second immersion in tap water rinse for 2 minutes at 104° F. with mild agitation. The panel was then rinsed with a gentle deionized water spray for 5 seconds. The panel was then placed in the conversion bath solution of Example E for 6 minutes at ambient temperature with mild agitation followed by a deionized water immersion rinse for 5 minutes at 77° F. with mild agitation followed by a second immersion rinse in deionized water for 5 minutes at ambient temperature. The panel was then rinsed with a gentle deionized water spray for 5 seconds. After, the panel was immersed in the seal solution of Example I for 1 minute at ambient temperature with intermittent agitation. The panel was then rinsed with a gentle deionized water spray for 5 seconds.

The panel was left to dry for a minimum of 18 hours at ambient conditions before being placed in a neutral salt spray cabinet operated according to ASTM B117 for 14 day corrosion testing. Corrosion performance was evaluated by counting the number of pits visible to the naked eye on the panel. Data are reported in Table 12.

Results are reported in Table 12 as the total number of pits across the face of the sample. Pits were counted as any corrosion event where white corrosion product was present and were counted with the unaided eye.

TABLE 12 Corrosion Performance (Pits) on Panels Treated According to Examples 1-7 Conver- Cleaner Deoxidizer sion Seal Pits Comp Example 1 A C E — 25 Comp Example 2 B D E — 10 Comp Example 3 A C E F 12 Example 4 A C E G 2 Example 5 B D E G 1 Example 6 A C E H 2 Example 7 A C E I 3

Panels were counted using the unaided eye.

A comparison of the number of pits counted on panels treated according to Examples 4-7 following 14 days of exposure to neutral salt spray results compared to those counted on the panel treated according to comparative Examples 1 and 2 shows the benefit of treating the substrate with a seal containing an ammonium-containing compound following treatment of the substrate with a conversion composition containing trivalent chromium. Evidence of the improvement is seen by the reduction in the number of pits on the surface of the treated substrate panels (Examples 4 and 6 had 2 pits, Example 5 had 1 pit, and Example 7 had 3 pits) after exposure to neutral salt spray for 14 days (ASTM B117), while comparative Example 1 had 25 pits and comparative Example 2 had 10 pits.

A comparison of the number of pits counted on panels treated according to Example 4 and Example 6 following 14 days of exposure to neutral salt spray compared to those counted on the panel treated according to comparative Example 3 shows the benefit of treating the substrate with a seal containing an ammonium-containing compound over a seal containing lithium and molybdenum following treatment of the substrate with a conversion composition containing trivalent chromium. Evidence of the improvement is seen by the reduction in the number of pits on the surface of the treated substrate (Example 4 and Example 6 each had 2 pits, while comparative Example 3 had 12 pits).

As shown in FIG. 1A and FIG. 1C, the fluoride level in a panel not treated with the ammonium-containing seal composition was about 7 atomic percent at the air-surface interface and increased to about 9 atomic percent at about 50 nm below the air-surface interface. In contrast, as shown in FIG. 1B and FIG. 1C, the fluoride level in a panel treated with the ammonium-containing seal composition following application of the TCP conversion composition had reduced fluoride content at the air-surface interface was reduced to about 2.5 atomic percent and had reduced fluoride content at about 50 nm below the air-surface interface to about 4 atomic percent. Notably, the fluoride content persists deeper below the air-substrate interface (i.e., to about 225 nm below the air-substrate interface) in a panel not treated with the ammonium-containing seal composition compared to a panel that was treated with the ammonium-containing seal composition (i.e., the fluoride content only persists to about 175 nm below the air-substrate interface). Additionally, the content of chromium and zirconium remain substantially intact regardless of whether the substrate was treated with the ammonium-containing seal composition or not. The reduction in fluoride content at and below the air-surface interface correlates with a reduction in pitting on the substrate surface (i.e., an improvement in corrosion performance).

Whereas specific aspects of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the claims and aspects appended and any and all equivalents thereof. 

1. A system for treating a substrate comprising: a conversion composition comprising trivalent chromium in an amount of 0.001 g/L to 20 g/L based on total weight of the conversion composition; and a sealing composition comprising an ammonium-containing compound.
 2. (canceled)
 3. The system of claim 1, wherein the conversion composition further comprises a coinhibitor.
 4. The system of claim 3, wherein the coinhibitor comprises a transition metal, a lanthanide series metal, and/or an azole, or combination thereof. 5.-6. (canceled)
 7. The system of claim 3, wherein a salt of the coinhibitor is present in the conversion composition in an amount of 0.001 g/L to 20 g/L.
 8. The system of claim 1, wherein the pH of the conversion composition is less than
 7. 9. The system of claim 1, wherein the ammonium of the ammonium-containing compound is present in the sealing composition in an amount of 100 ppm to 1,500 ppm based on total weight of the sealing composition.
 10. The system of any of the preceding claims claim 1, wherein the sealing composition has a pH of 5 to
 11. 11. The system of claim 1, wherein the sealing composition further comprises a Group IVB metal, a carbonate, a sulfate, a nitrate, an acetate, a hydroxide, a halogen, a silicate, a phosphate or any combination thereof.
 12. The system of claim 11, wherein the Group IVB metal is present in the sealing composition in an amount of 250 ppm to 3,800 ppm based on total weight of the sealing composition.
 13. (canceled)
 14. The system of claim 1, further comprising a cleaner composition, a deoxidizing composition, an indicator composition, and/or a film-forming composition.
 15. (canceled)
 16. A method of treating a substrate with the system of claim 1, the method comprising: contacting at least a portion of a surface of the substrate with the conversion composition; and contacting at least a portion of the surface that has been contacted with the conversion composition with the sealing composition.
 17. The method of claim 16, further comprising contacting at least a portion of the surface with a cleaner composition and/or a film-forming composition.
 18. The method of claim 16, wherein the substrate is deoxidized using mechanical deoxidation and/or chemical deoxidation.
 19. (canceled)
 20. A substrate comprising a surface having a fluoride content of less than 7 atomic percent at the air-surface interface as measured by XPS depth profiling (using a Physical Electronics VersaProbe II instrument equipped with a monochromatic Al kα x-ray source (hv=1,486.7 eV) and a concentric hemispherical analyzer) and/or a fluoride content of less than 4.5 atomic percent 50 nm to 100 nm below the air-surface interface as measured by XPS depth profiling (using a Physical Electronics VersaProbe II instrument equipped with a monochromatic Al kα x-ray source (hv=1,486.7 eV) and a concentric hemispherical analyzer).
 21. A substrate having a surface, wherein at least a portion of the surface is treated with the system of claim
 1. 22. A substrate having a surface, wherein at least a portion of the surface is treated with the method of claim
 16. 23. The substrate of claim 21, wherein: (a) the substrate has a fluoride content of less than 7 atomic percent at the air-surface interface as measured by XPS depth profiling (using a Physical Electronics VersaProbe II instrument equipped with a monochromatic Al kα x-ray source (hv=1,486.7 eV) and a concentric hemispherical analyzer); (b) the substrate has a fluoride content of less than 4.5 atomic percent 50 nm to 100 nm below the air-surface interface as measured by XPS depth profiling (using a Physical Electronics VersaProbe II instrument equipped with a monochromic Al kα x-ray source (hv=1,486.7 eV) and a concentric hemispherical analyzer); (c) the substrate has a fluoride content of that is reduced by at least 30% at the air-surface interface and up to 150 nm below the air-surface interface compared to a substrate treated with the conversion composition and a sealing composition that does not contain an ammonium-containing compound as measured by XPS depth profiling (using a Physical Electronics VersaProbe II instrument equipped with a monochromatic Al kα x-ray source (hv=1,486.7 eV) and a concentric hemispherical analyzer); and/or (d) a number of pits on the surface is reduced by at least 10% compared to a substrate treated with the conversion composition and a sealing composition that does not contain an ammonium-containing compound.
 24. The substrate of claim 21, wherein the substrate comprises a vehicle, a part, an article, or combinations thereof.
 25. The substrate of claim 24, wherein the vehicle comprises an automobile or an aircraft.
 26. The substrate of claim 21, wherein the substrate comprises aluminum or an aluminum alloy. 